It's a time of year thing, I think ??
My DS was always in bed at 7.30/45, but when he turned 5 he was up till 9ish during the summer, despite long days in childcare & being physically active, plus blackout blinds.
He's now 6 & we put the lights out at 8.30; he plays in his room till 9ish & wakes up at 6.30ish. Weep.